Improvement in steam-boilers



UNITED STATES PATENT OFFICE.

HENRY 'HOFFMAN, OF NEW YORK, N. Y.

IMPROVEMENT IN STEAM-BOILERS.

Specification forming part of Letters Patent No. 31,542, dated February26, 1861,

To all whom it may concern:

Be it known that I, HENRY HOFFMAN, of the city, county, and State ofNewYork, have'invented a new and Improved Steam-Boiler; and I do herebydeclare that the following is a full, clear, and exact description ofthe same, reference being had to the accompanying drawings, forming apart of this specification, in which- Figure 1 represents a longitudinalvertical section of my invention; Fig. 2, ahorizontal section of thesame.

Similar letters of reference indicate corresponding parts in bothfigures.

To enable those skilled in the art to make and use my invention, I willproceed to describe its construction and operation with reference to thedrawings.

My invention relates particularly to that class of boilers in which aseries of horizontal tubes conduct the products of combustion from thefire-box through the water to the smoke-chamber. With ordinary boilersof Ithis class the heat from` the fire is allowed to pass into thehorizontal tubes without obstruction,and the Water which surrounds thelire-box, and which is generally supposed to be exposed to the highestheat, is heated comparatively little, and Inuch of the heatingsurface ofthe boiler is lost. To avoid these defects, I have placed in thetire-box Aof my boiler two horizontal partitions, B C, thereby formingthree compartments-the tire-space or furnace a, the Water-space b, andthe combustion-chamber c. The fire-space a. communicates with thecombustion-chamber c by a series of vertical lines, D, which are securedin the partitions or tube-sheets B C, as clearly shown in Fig. 1 in thedrawings.

' The Water-space b communicates, by means of tubes E, with thewater-space F of the boiler, and a series of water-legs, G, are insertedinto the top plate, d, of the fire-box, extending down into thecombustion chamber c, as shown in Fig. 1. The tubes E form the bracesbetween the top plate of the lire-box and the tube-sheet' C, and thewater circulates freely Afrom the water-space b through the tubes E tothe water-space F of the b'oiler.

A door, H, in ther side of the fire-box, admits of` introducing the fuelto the grate I, and another door, J, gives access to thecombustion-chamber c for the purpose of cleaning the same. Thehorizontal tubes or lues K extend from the side of the combustionchamberto the end of the boiler, being inserted into the tube-sheet e in theordinary manner, and a dome, L, which forms the steam-space, rises abovethe lire-box.

The fire is built on the grate I, and on being lighted the products ofcombustion pass up through the vertical lues D into thecombustion-chamber c and through the horizontal flues K to thesmoke-stack or chimney. Those portions of my boiler which are exposed tothe strongestheat-viz., the partition-plate or tube-sheet B and thevertical flues D-are under all circumstances covered or surrounded bywater, there being no danger that the water will ever get low enough toexpose'any of said parts, and the heating-surface is further increasedby the vertical tubes E and the water-legs G, all of which are exposedfrom all sides tothe direct action of the heat. By turning the heat fromthe combustionchamber off into the horizontal flues K it Vis retained insaid chamber suiciently long to exert its influence on the surroundingwater, and still the draft is not impaired, and the Whole body of watercontained in the boiler is thoroughly heated. By these means an extendedheating-surface is obtained in a boiler of comparatively smalldimensions, and a small quantity of fuel is suliicient to evaporate alarge quantity of water and to produce steam enough for a comparativelylarge en-` glue.

Having thus fully 4described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

The particular arrangement of the legs G G, combustion-chamber c, andtubes E, with the tube-sheets B C and iiues D K, in the manner hereinshown and described.

HENRY HOFFMAN. Witnesses:

C. W. CoU'rAU,

- JAMES LAIRD.

